U.S. Pat. No. 5,207,837 discloses a method of disposing of hospital garments and like fabric articles which are not water soluble at temperatures below normal body temperature (37 degrees C.; 98.6 degrees F.) and which are water soluble at temperatures above normal body temperature, so as to be disposable by dissolution in hot water. See also related U.S. Pat. No. 5,181,966 disclosing hot water soluble packaging materials, and U.S. Pat. No. 5,181,967 disclosing a method for disposal of hot water soluble utensils.
As described in U.S. Pat. No. 5,207,837, hospital patient care generates considerable quantities of infectious medical waste. There has been a general conversion from reusable, cleanable items, to disposable items. These conversions were made to promote antiseptic techniques in patient care and to decrease the potential for cross infections between patients, staff and the general public.
The best way to deal with infectious medical waste, the patent states, is to disinfect it at the point of generation and dispose of the treated medical waste with minimum handling and on site storage.
The need for an effective way to dispose of medical waste calls for establishment of an exposure control plan, the containment of specimens of blood or other potentially infectious materials and the general tightening of precautionary measures to minimize the spread of disease. A safe and effective way to dispose of hospital waste in the form of soiled garments and apparel would greatly facilitate compliance.
Disposable medical fabrics are generally currently composed of thermoplastic fibers such as polyethylene, polypropylene, polyesters, polyamides and acrylics. These fabrics can also include mixtures of thermoset fibers such as polyimides, polyarimids and cellulosics. They are typically 10-100 grams per square yard in weight and can be woven, knitted or otherwise formed by methods well known to those in the textile arts while the nonwovens can be thermobonded, hydroentangled, wet-laid or needle punched, again by methods which are well known in the textile arts.
Although there is clearly a benefit in the use of disposables in the medical arts, nonbiodegradable disposables are posing a serious problem. Landfill sites are becoming increasingly burdened with disposables which do not biodegrade for hundreds of years, if ever. As landfill sites become fully exploited, new sites must be found, which are vigorously opposed by residents located proximate to proposed site locations.
U.S. Pat. No. 5,207,837 proposes to solve these problems by the provision of fabrics which are not soluble at temperatures customarily encountered in hospitals, i.e., body temperature and below, and which are soluble at temperatures above normal body temperature, preferably above 50 degrees C. (122 degrees F.) and most preferably in the range of 80-90 degrees C. (176-194 degrees F.). Working with such a hot water soluble polymer would prevent involuntary solubilization upon exposure to body fluids, yet remain viable for subsequent hot water dissolution and disposal. The patent contemplated that disposal in a hot water bath, such as a washing machine at or near the boiling point of water and dedicated to solubilizing garments, linens and other useful articles would also be an effective disinfecting media. As such, two objectives would be accomplished, namely, that the polymer or sheets would be disinfected and would be solubilized for disposal through the sewer system. Not only would this lessen the burden imposed on landfill sites but liquid sewer disposal would prove a comparative low cost technique in ridding the user of such used garments.
According to the patent, polymer or sheet materials useful for the purpose comprise polyvinyl alcohol with or without acetyl groups, cross-linked or uncross-linked. Ideally, the garments are comprised of polyvinyl alcohol homopolymer that has been highly crystallized by post drawing or heat annealing. Ideal for use would be a highly crystallized totally saponified polyvinyl acetate, such as the polyvinyl alcohol available from Air Products under the trademark Vinex 1003.
However, polyvinyl alcohols that are highly crystallized by post drawing or heat annealing, or by total or substantially total saponification or hydrolyzation, are expensive, very difficult to process, and soluble only at temperatures approaching the boiling point of water. A more economical, more easily processed, and more readily solubilized alternative is required.